In general, mobile communication systems were developed to provide voice call services, supporting users' mobility. Mobile communication systems have increased the service field to data services as well as voice call services, and have recently been developed so that they can provide high speed data services. As mobile communication systems evolve to provide a wider range of services, they face lack of resources and users' demands for high speed data services. Therefore, the development of mobile communication systems is required.
In order to comply with users' demands, Long term Evolution (LTE) that has been developed as a next generation communication system is standardized in the 3rd Generation Partnership Project (3GPP). LTE is a technology to implement high speed packet-based communication supporting a maximum transmission rate of up to 100 Mbps. To this end, various proposals have been discussed. As an example, a scheme has been proposed to reduce the number of nodes on communication paths by simplifying network architecture. Another scheme has been proposed to apply radio protocols to wireless channels as close as possible.
Meanwhile, unlike a voice service, a data service determines its resources, etc., which can be allocated according to the amount of data to be transmitted and the channel quality. Therefore, in a wireless communication system such as a mobile communication system, a scheduler performs the management, such as, the allocation of transmission resources, etc., considering an amount of resources for the transmission, the channel quality, an amount of data, etc. This is also performed the same by an LTE as one of the next generation mobile communication systems, in such a way that a scheduler located in an eNB performs the management and allocation of wireless transmission resources.
In recent LTE communication systems, discussion have been made about LTE-Advanced (LTE-A) that is combined with various types of new technologies to enhance the transfer rate. LTE-A systems also include the improvement of Multimedia Broadcast Multicast Service (MBMS). MBMS is referred to as a broadcast service provided via an LTE system.
Service providers must optimize a service area for MBMS services as well as that for unicast communication. In particular, if UE moves between cells, a scheme is required to provide the UE with continuous MBMS services.